220 MARINE BIOLOGICAL LABORATORY. 



the surface of the body midway between the roots of 

 the facial and glossopharyngeal nerves as they issue 

 from the brain. At the point of junction the two half- 

 pores united into a single pore, which in some fish 

 forms {e.g. Torpedo) persists as the outer opening of 

 the endolymphatic duct, and the only persisting indica- 

 tion of the separate origin of these organs and their 

 canals is their nerve supply. It is a necessary conse- 

 quence of the great functional differentiation which 

 the ear organs have suffered that their nerves should 

 also become much increased in size, and instead of 

 appearing now as nei've branches they have become 

 really larger than the parent nerves from which they 

 arose. 



As a prelude to the little I have to say on the 

 physiology of the internal ear, I wish to emphasize 

 the following considerations : We have very slender 

 foundation indeed for correctly judging of the functional 

 relations of the integral parts of the internal ear, and 

 what we have is largely speculative, based on our 

 knowledge of the structure of the parts. 



What we need at the present time is physiological 

 experimentation. First of all, an extended series of 

 varied, careful, and unbiassed experiments on the sense- 

 organs of the lateral line system of the lower verte- 

 brates, to determine their functions, and then more 

 experiments on the internal ear of the least differen- 

 tiated representatives of our type, to determine what 

 functional modifications have arisen during the trans- 

 formation processes. Finally, the combination of the 

 knowledge thus gained, with the results of experiments 

 upon the human subject. 



